JP2008-202724A discloses a spring return type control valve as one example of a valve device. This control valve includes a valving element (spool) housed in a sliding hole of a valve body, a pilot chamber formed on one end of the sliding hole, a drain chamber formed on the other end of the sliding hole, and a return spring housed in the pilot chamber.
When pilot pressure is supplied to the pilot chamber, the spool moves toward the drain chamber due to the pilot pressure. When the supply of the pilot pressure to the pilot chamber is blocked, the spool moves toward the pilot chamber due to a restoring force of the return spring.
A drain port is formed in a drain chamber wall that defines the drain chamber. Working oil in the drain chamber is discharged to a tank via the drain port as drain fluid.